6
TD_MRI1_06.05_GB
Voltage measuring for the directional detection:
Figure 3.4:
Measuring of the phase voltages for the directional
detection at overcurrent, short-circuit or earth-fault
protection (I>, I>>, I
E>
and I
E>>
).
For details on the connection of ER/XR-unit type c.t.s,
see para 4.5.
I>
I>
I>
A3
L1
U1
U2
A5
L2
A7
L3
A2
N
U3
L1
L2
L3
a
b
c
Figure 3.5:
Voltage transformer in V-connection for the
directional detection at overcurrent and short-circuit
protection.
The V-connection can not be applied at earth fault di-
rectional feature.
3.1.1
Analog input circuits
The protection unit receives the analog input signals of
the phase currents IL1 (B3-B4), IL2 (B5-B6), IL3 B7-B8)
and the current IE (B1-B2), phase voltages U1 (A3),
U2 (A5), U3 (A7) with A2 as star point, each via
separate input transformers.
The constantly detected current measuring values are
galvanically decoupled, filtered and finally fed to the
analog/digital converter.
For the unit type with earth fault directional features
(ER/XR-relay type) the residual voltage U
E
in the sec-
ondary circuit of the voltage transformers is internally
formed.
In case no directional feature for the phase current
path is necessary the residual voltage from the open
delta winding can directly be connected to A3 and
A2.
See Chapter 4.4 for voltage transformer connections
on isolated/compensated systems.
3.1.2
Output relays of
MRI1
-relays
The
MRI1
is equipped with 5 output relays. Apart from
the relay for self-supervision, all protective functions
can be optionally assigned:
•
Relay 1: C1, D1, E1 and C2, D2, E2
•
Relay 2: C3, D3, E3 and C4, D4, E4
•
Relay 3: C5, D5, E5
•
Relay 4: C6, D6, E6
•
Self-supervision C7, D7, E7
All trip and alarm relays are working current relays,
the relay for self supervision is an idle current relay.
3.1.3
Blocking input
The blocking functions adjusted before will be blocked
if an auxiliary voltage is connected to (terminals)
D8/E8. (See chapter 5.2.25)
3.1.4
External reset input
Please refer to chapter 5.5.